1. Technical Field
Various embodiments of the present invention relate to a circuit device, an oscillator, an electronic apparatus, and a vehicle.
2. Related Art
In the related art, there is an oscillator such as an oven controlled crystal oscillator (OCXO) or a temperature compensated crystal oscillator (TCXO). For example, the OCXO is used as a reference signal source in a base station, a network router, a measurement apparatus, and the like. There is a need for a highly accurate oscillation frequency in an oscillator such as the OCXO or the TCXO.
Regarding the related art of such an oscillator, there is a technique disclosed in JP-A-2015-82815. In this related art, aging correction is performed on an oscillation frequency in order to obtain a highly accurate oscillation frequency. Specifically, there are provided a storage which stores correspondence relationship information between a correction value of a control voltage for an oscillation frequency and the elapsed time, and an elapsed time measurer. Aging correction is performed on the basis of the correspondence relationship information between a correction value and the elapsed time, stored in the storage, and the elapsed time measured by the elapsed time measurer.
As mentioned above, there is a need for a highly accurate oscillation frequency of an oscillation signal in an oscillator such as the OCXO or the TCXO. A clock signal having a frequency which is different from an oscillation frequency may be required to be supplied by an external system.
On the other hand, a digital interface may be provided in a circuit device in order to cope with an application such as forming a loop of a PLL circuit by using an external frequency control data generator of the circuit device.
However, if such a digital interface is provided, it has been proved that there is a concern that the accuracy of a clock signal or an oscillation signal is reduced due to phase noise or the like caused by communication noise in the digital interface.